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What’s The Health of Your Hoses?

Posted: March 2, 2014

By: Story and photos by Deane Hislop

Does your boat have hardening of the arteries? Marine hoses are equivalent to arteries and veins in the human body; they transfer important fluids throughout your boat. The arteries on your boat may include various forms of hoses, including flexible hoses, tubing, conduit, ducting, exhaust and fuel lines. They connect, service and protect virtually all the critical equipment and systems. Therefore, the failure of a hose can have catastrophic effects such as an explosion, a fire, flooding and sinking.

An old hose on an open raw-water intake that lets go and floods the bilge could sink your boat at the dock. Some cautious skippers close the seacocks every time they leave their boat for an extended period; the more practical solution is to inspect and maintain the fittings and hoses, and to change them as needed.

All hoses will fail over time, so they need to be inspected once a year. It’s alarming how many boat owners take their hoses for granted, replacing them only after a leak or some other problem occurs. But by then, the contents of your fuel tank or holding tank are sloshing around in the bilge.

Rubber is cured from its natural gummy state with a combination of sulphur, peroxide, heat and pressure. A rubber hose’s reliability and life expectancy depend on the heat it has been exposed to. Additional heat increases the “cure,” which causes the hose to become hard and brittle. It’s possible for a hose to look fine until a big impact or other occurrence causes it to bend or flex. Remember: A new hose is resilient. An old hose cracks and breaks.

Spring is a great time to inspect all of your hoses, as you won’t be wasting valuable cruising time. Step one, for boat owners who have been less than diligent in the past, is locating and tracing all of your boat’s fluid systems: the raw-water cooling hoses, exhaust hoses, AC intakes, potable water supply lines and, yes, even the gray- and black-water sewage lines.

The most common failure point is at the end fittings, and seasonal freezing and thawing can accelerate the wear process, as residual amounts of moisture can creep into the fitting and loosen and compromise the seal.

If a connection looks suspect but the hose appears to be in otherwise good condition, you may be able to trim the hose end and reattach it. But in most cases, you’re better off buying a new hose, and new hose clamps, too. The most commonly used clamp is the worm-gear driven perforated band-style clamp. T-bolt clamps utilize both a bolt and a nut to tighten the band and are designed for larger diameter hoses and high-vibration connections such as exhaust.

When it comes to buying clamps, it’s worth spending a bit more. On less expensive clamps, the perforated slots are often produced with stamping presses that leave little ridges on the underside, and the ridges will grab on to the hose as you tighten, resulting in an uneven seal. Even good-quality stainless clamps have a way of corroding when left in a wet environment. A few-year-old clamp that seems fine on the surface could be close to failure, so check them regularly.

The common perception is that it’s best to crank down hard on a clamp to secure it, but that can cause a blowout by squeezing the hose material too hard and reducing the thickness of the hose. Clamps should be tightened to around 35 inch/pounds of torque, which happens to be about as tight as you can get it with a good manual screwdriver. Double clamping is recommended, if possible, but make sure both clamps sit firmly on the fitting lip and don’t overhang onto an unsupported section of the hose, as this could cause failure. And since most hoses have some give to them and will contract a bit under pressure, it’s a good idea to come back an hour or two after you first install the clamp and give it one more tweak to ensure the seal.